1. Field of the Invention
The invention relates to a process for the isolation of hydroxy fatty acid derivatives from Convolvulaceae plants by extracting plants like leaves, stems, seeds and in particular roots and/or tubers of said plants with an extraction agent and subsequently subjecting the extraction liquor to a hydrolysis step.
2. Description of the Related Art Including Information Disclosed under 37 CFR .sctn..sctn.1.97-1.99
From Planta Medica 9 (1961), the Chemistry of some Convolvulaceous Resins part I, pages 102-116 it is known to isolate Vera Cruz jalap resin from dried tubercles of Ipomoea purga Hayne by extracting the substance with alcohol, evaporating off most of the alcohol, pouring the alcoholic liquor into a large volume of water and filtering off the precipitated resin which is then washed with water and dried. Thereupon this jalap resin is divided into an ether insoluble fraction and an ether soluble fraction. Both said fractions are chemically examined by two hydrolysis methods i.e.
a) alkaline hydrolysis using baryta followed by acid hydrolysis and PA1 b) direct acid hydrolysis. PA1 a) extracting these parts of the Convolvulaceae plants with the help of an organic solvent; PA1 b) removing the solvent for at least the main part and dispersing the obtained material in water, followed by a hydrolysis in a pH-range of 1-9 and PA1 c) recovering the obtained hydroxy fatty acid derivative(s) from the aqueous dispersion.
Above method (b) was carried out by dissolving the fraction of the jalap resin in question i.e. the ether soluble fraction or the ether insoluble fraction in ethanol (96%) and acidifying the solution with sulphuric acid until the acid content was about 5%. The ethanolic solution was refluxed for several hours after which most of the alcohol was removed and the residue steam distilled. The remaining aqueous liquor was allowed to stand overnight. During that period a solid matter precipitated which was filtered off or dissolved in chloroform for identification of the obtained hydorxy acids. Dependent on the starting fraction several long chain hydroxy fatty acids could be identified like 3.11-dihydroxy myristic acid and a monohydroxy pentadecanoic acid in the ether insoluble portion and jalapinolic acid (11-hydroxy palmitic acid) in the ether soluble portion.
In Planta Medica 9 (1961), pages 141-145, the Chemistry of some Convolvulaceous Resins part II, the composition of Brazilian jalap resin, obtained from dried sliced tubercles of Merremia tuberosa (L) Rendle and of Operculina macrocarpa (L) Urban was investigated. The applied investigation method for said resin was based on a subdivision of the resin in an ether insoluble and an ether soluble fraction and then subjecting said fractions to an alkaline hydrolysis followed by an acid hydrolysis. Dependent on the starting fraction several long chain hydroxy fatty acids could be identified like a dihydroxy palmitic acid and probably a trihydroxy myristic acid as well as jalapinolic acid (11-hydroxy palmitic acid).
Further in Planta Medica 9 (1961), pages 146-152, the Chemistry of some Convolvulaceous Resins part III, the composition of Tampico, Ipomoaea and Scammony resins obtained from dried tubercles of Ipomoea simulans Hanbury, dried sliced tubercles of Ipomoea orizabensis and dried roots of Convolvulus scammonia L. respectively were investigated.
Concerning the Tampico jalap resin which was completely soluble in ether, the chemical investigation was carried out by means of an alkaline hydrolysis followed by acid hydrolysis. One of the identified fatty acids was jalapinolic acid.
The Ipomoea resin was divided in an ether insoluble and an ether soluble fraction, which fractions subsequently were subjected to an alkaline hydrolysis and an acid hydrolysis. The same procedure was carried out with Scammony resin. From the results it revealed that said last two resins have to be considered identical and contain several long chain hydroxy fatty acids like jalapinolic acid.
However, from the above it is clear that the isolation methods described in the above references are quite laborous and complicated. For instance several solvents like ether, ethanol and, if required, chloroform are applied.
Summarized it is brought to the fore that the above discussed prior art refer to inadequate methods for isolating the long chain hydroxy fatty acids from the jalap resins or any other suitable source which are not or hardly suitable for use on a large scale. Nevertheless, there is a need for a process for isolating these hydroxy acids on an industrial scale as they are important starting materials for preparing laxatives, lactones and ingredients for lubricating greases.